Here's an interesting article at CNN.com discussing Red Hat's possible entry into the handheld market. You'll recall that the company recently acquired Cygnus; RH is now looking to use that company's small device expertise to interface handheld computers with Linux.
The company's vision (well, part of it anyway) is to have handhelds replace laptops to handle administrative tasks on Linux servers. They're working on eCos, or Embeded Cygnus Operating System (billed as a possible competitor to CE) as well as an API allowing simultaneous development for Linux and eCos. I wonder how long until somebody comes out with a PDA in the shape of a pengiun.